This project is oriented toward applying roentgen contrast techniques to investigation of the cardiovascular system in a variety of experimental and clinical situations. It combines the demonstrated capacity for high-grade morphologic display of angiography with physiologic methods to study problems in which the two approaches are required for optimal analysis. Furthermore, it focuses on a number of problems in which new knowledge may be directly applicable to current surgical approaches to heart disease. Thus, a major continuing objective is to place the investigation of the coronary circulation in man on a rational basis pre- and postoperatively. The usefulness of radioactive nuclides in quantitating coronary blood flow is under investigation both at rest and under stress as well as in the postoperative evaluation of myocardial revascularization. Two additional techniques of quantitating hemodynamically significant stenosis--videodensitometry and processed computerized densitometric scanning--will be explored, and the relationship of the severity of stenosis to the degree of postsurgical augmentation of coronary blood flow will be defined. The application of computerized axial tomography to the study of ventricular wall motion in coronary disease and to the delineation of infarcted tissue will be explored. The hemodynamic, radiologic, and morphologic changes accompanying experimental myocardopathy are also being investigated. Additional studies will concentrate on determinants of collateral vessel formation; the intercoronary collateral circulation; vasa vasorum blood flow in the aortic wall during atheromatosis and after trauma; and the determinants of renal perfusion in acute renal failure states. BIBLIOGRAPHIC REFERENCES: Abrams, H.L.: Angiographic agents. IN Radiographic Contrast Media (Skucas J., ed). College Park, Maryland: University Park Press, 1977. Brown, C.B., Drum, D.E., Hollenberg, N.K.: A smooth muscle active factor isolated from renal cortex of the rabbit. Am. J. Physiol. 232:F84-F91, Feb. 1977.